My 4" 500 Mag has got one of the smallest if not the smallest cylinder gaps of any revolver I've ever owned and I've owned quite a few revolvers in my 55 years. I'm surprised that it doesn't start binding up as it heats up and gets dirty but it doesn't. I haven't measured it but it looks like it can't be over a .001" wide.

From what I've read on cylinder gap pressure lost there is some people that don't believe you hardly lose any velocity until you get a sizable cylinder gap. At least not anything near 200 FPS. I believe I'd be checking the crono machine because there's no way that small of a gap will lose 200 FPS. Is it possible you may using some bad powder? Or are you using bullets that are to small for the bore? Because if you are using a max loads and only have .002 gap then it's going to have the same or better results as any gun out there. It has to be the machine or the powder your using I think.

500Mag

I had a chance this evening to sit down at the reloading table and I think I've made some headway. I want ahead and ran all of the cases through the expander just to true them up and then ran all of them back through the resizer. After that all of the bullets appear to be seating tight again like they had been in the past. I've got just shy of 30 bullets on hand for testing. I've loaded two sets of 5 w/ LilGun. One at 41 gr. and the other at 42. I also have a supply of H-4227 on hand that I might use to load a couple of sets and a friend has offered me some H-110. Now that I have the tension problem fixed and can concentrate on the powders maybe I can get information that's a little more conclusive. We'll know more this weekend.

JRO45 Getting that velocity with a 500 gr bullet is probably running pressure in the high 50K range. I would not go any higher. Hornady in their data went only to 32.5 to hold pressures to 48000 so they could use WLP primers. They clocked 1300 fps out of an S & W 83/8th's gun.

When you add a mag rifle primer that should raise pressure then their data show it takes 2.9 gr to gain 100 fps on average we seeit would probably take 35.5 gr of H110 to get 1400.in the best case senario I would say pressures are in the 55000 psi range.

4100 from the data I've seen is probably slightly faster burning than H110 so I would stop right where you are and not go any higher until I confered with Accurate Arms on the load you are using and where 4100 falls in the burning rate situation.

I looked at AA data again and it does seem that 4100 is very close to H110 but I still wouldn't go any higher.

I kinda like AA 1680 as it gives higher loading density than H110.

Hornady listed 40.2 gr AA1680 at 1350 using a WLP and holding pressure within 48000 psi.

That powder is probably the best when it comes to loading density and velocity.



I know you will give me the old: I know all of the information that you gave me Me_Plat. I've been loading my ammo long before Columbus came over and I know what I am doing type thing. So be it. I just wanted to tell you this infomation anyway as the are no magical powders. It takes pressure to get velocity plain and simple.

Me_Plat

Thanks for the tip. I thought that was kinda fast for a 500gr bullet. But the gun was checked out to 80,000 PSI by S&W when the new gun was checked out.Thats what I heard and I couldn't understand why all the rounds for it were loaded at a lower presure.I would say that factory loads should at least be in the 50,000 psi range but I know there not. I guess they didn't want to get into the rifle psi range.

Alright, well I spent several hours at the range today and the results were disappointing to say the least. I actually expected them, but that doesn't mean that I like it. Here's the info on the loads that I shot today. The highest velocity was just under 1650. Atleast before I sent the gun in I was consistently in the 1700's. What the hell is the matter with this gun? What do I tell S&W so that they'll fix it? They already asked last time "Have you shot any factory ammo through it?". Well, I haven't, and to be honest, I'm going to try to avoid that. The stuff is just too damned expensive. Roughly $40 for 12 rounds? C'mon. I have too much data that says there's another problem. Neck tension is good, crimp is tight. Other than a loose bore on this barrel that they just put on, what else is there? Hopefully with the information below you guys can give me more insight. I really like the gun, but I'm wondering if I shouldn't try to sell it and get another one?

41.5 gr. H-4227
Highest - 1595, avg. 1582

42.5 gr. H-4227
Highest - 1644, avg. 1625

42. gr. H-110
Highest 1638, avg. 1535

43 gr. H-110
Highest - 1593, avg. 1549

41. gr. H-Li'l Gun
Highest 1612, avg. 1554

42. gr. H-Li'l Gun
Highest 1533, avg. 1510